Our overall goal in this project is to vastly improve patient care in the practice of image guided neurovascular diagnosis and interventions by providing vastly improved images with minimal increased radiation effective dose. The basic concept is that for many diagnoses and for most interventions, the best image is needed only over the region of interest around the pathology, hence a detector far superior in image quality to standard x-ray image intensifiers or flat panels but small in field of view could provide this improvement in diagnosis and image guidance, hence greatly improving the intervention itself. While we have accomplished in the previous funded period the specific aims of constructing such a detector and testing it in phantoms and animals, we have only recently introduced this Micro-Angiographic Fluoroscope (MAF) to guide human interventions. The MAF has had some outstanding initial results including major positive impacts on some of the interventions leading to improved patient procedures at substantially reduced effective doses. Our goals for continuing the MAF project fall into two broad groupings: I) developing further improvements in the detector system technology and II) doing continued human testing as each development is implemented, so that at the conclusion of this renewed project we will have enough results to justify the final translation of our research into manufactured medical systems that provide the new standard of care in image guided endovascular interventions. Although we believe the basic ROI imaging concepts being developed here may be applicable to all endovascular procedures including cardio and peripheral vascular diagnoses and interventions and to pediatric studies, to maintain project focus, we emphasize neurovascular applications. We will improve the detector system technology by: optimally selecting and evaluating components such as CsI thickness and type; implementing and evaluating spatial as well as temporal noise reduction filtering in real-time as well as studying methods of reducing patient vessel motion image degradation; improving the detector construction for stability and compactness; studying ROI CBCT, bi-plane MAFs, and automatic dose and other objective parameter tracking; and studying ways to increase the field of view. We will do human testing and evaluate the impact of the MAF technology on various neurovascular applications such as on aneurysm coiling, stent and distal protection device placement, determination and treatment of arterio- venous malformation niduses, flow and flow modifying devices, visualizing (hence preserving) small but very important perforator vessels, guiding of thrombolysis and deployment of clot removal devices for acute stroke, better determining morphology of complex pathology, and tracking the MAF dose, usage time and other objective operating parameters, as well as calculating the changes in effective dose for MAF use. We will correlate MAF use and these procedural parameters to standard patient outcome metrics.